Various processes for producing metal carbide and nitride compositions are known in the prior art. The scientific literature in this area describes three main access routes for the formation of these materials, particularly for the production of silicon nitride powders. These methods include gas phase reactions with halosilane and methane or ammonia, direct carbonization or nitridation from silicon and carbon or nitrogen and carbothermal reduction in the presence of a neutral or nitrogen atmosphere from silica and carbon (see, e.g., F. K. Van Dijen, et al., 117 Spechsaal (1984), pps. 627-9). In addition, metal carbide or nitride powders may also be produced on a laboratory scale by reactions requiring initiation by lasers or plasmas.
Unlike the laser or plasma techniques mentioned above, which result in the formation of carbides or nitrides having a large specific surface area, i.e., .gtoreq.100-150 m.sup.2 /g (see, e.g., Y. Kizaki, et al. 24 Japanese Journal of Applied Physics (July, 1985) pps. 800-5 or Y. Suyama, et al. 64 Am. Ceram. Soc. Bul. (1985) p. 1356-9), the carbothermal reduction method normally leads to the formation of carbide or nitride powders having a surface area of &lt;20 m.sup.2 /g. For example, the article by Van Dijen, discussed above, recites a value of 10-15 m.sup.2 /g as the maximum value which may be obtained in an optimized reaction; D. L. Segal, Chemistry & Industry (August 19, 1985) pps. 544-5 proposes a value of 5 m.sup.2 /g and S. C. Zhang, et al., 67 J. Am. Cer. Soc., pps. 691-5 discloses 10.3 m.sup.2 /g.